Heavy duty truck tires with a relatively thick tread region cross-section typically experience a significant heat build up and a corresponding increase in operating temperature as the truck tire is being used on an associated vehicle.
Such heavy duty tire internal heat buildup under heavy loads is considered herein to be significantly different from internal heat buildup generated in high performance light duty tires (e.g. passenger automobile tire and light duty truck tires). Heat build up in a heavy duty tire tread (e.g. heavy duty truck tire tread) during the working of such heavy duty tires under load can be of sufficient magnitude to cause such heavy duty tires to operate at relatively high temperatures and thereby have an impact upon their long term heat durability. Such heat buildup may also result from relatively high hysteresis in the tread compound, indicative of relatively higher rolling resistance and consequent fuel use.
A heavy duty tire is considered to be a tire having a minimum load bearing capacity of 4,000 pounds (1814 kg) and therefore is considered to be differentiated from a light duty tire having a maximum load bearing capacity of 3,500 (1587 kg), preferably a maximum load bearing capacity of 3,000 pounds (1361 kg). Reference: The Tire and Rim Association Handbook.